Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Chronic progressive multiple sclerosis (MS): The safety and effectiveness of using this medication by people with chronic progressive MS have not been established. Currently, natalizumab is only recommended for people with the relapsing-remitting form of MS.
Infections: Natalizumab may increase the risk of infections. If you notice any signs of an infection such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness, contact your doctor immediately.
Infusion-related reactions: Some people may experience an infusion-related reaction, including headache, dizziness, fatigue, hives, itching, and chills, up to 2 hours after the start of an infusion. If you notice these symptoms, let your doctor know right away.
Kidney function: If you have kidney disease or decreased kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Natalizumab may cause damage to the liver. If you have liver disease or decreased liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
If you experience symptoms of liver problems (e.g., abdominal pain, persistent vomiting, feeling unwell, fever, itching, yellowing of the skin and eyes, dark urine), contact your doctor immediately.
Progressive multifocal leukoencephalopathy (PML): Natalizumab has been associated with an increased risk of a rare brain infection called progressive multifocal leukoencephalopathy (PML), which can lead to disability or death. The risk of developing this infection increases with the length of time natalizumab is used.
Signs and symptoms of PML include progressive weakness on one side of the body; clumsiness of limbs; vision disturbances; changes in thinking, memory, and orientation; confusion; and personality changes. Some of the symptoms are similar to MS, so if you develop any of these symptoms or any other unusual symptoms, or if your MS gets worse, contact your doctor immediately. Your doctor should do an MRI scan before you start natalizumab to help distinguish a subsequent MS relapse from PML.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if natalizumab passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children and adolescents under 18 years of age.